Automatic oiling device for chain saws



limited St tes Patent Ofiice Patented July 28, 1959 Austin Gudmundsen,Inglewood, Calif., assignor to McCulloch Motors Corporation, LosAngeles, Calif., a corporation of Wisconsin Application November 23,1956, Serial No. 624,091

Claims. (Cl. 184-15) This invention relates to an automatic lubricatingsystem for use with two cycle engines and relates in particular to meansfor automatically oiling the saw chain and saw chain supporting bar of achain saw de- Wn'ce powered by a crankcase scavenged two cycle engine ofthe type in which the lubricating oil is mixed with the fuel.

Chain saw devices of the type used for cutting timber require frequentapplication of lubricating oil to the saw blades chain supporting grooveand to the chain. For this purpose a small oil tank with hand operatedpiston pump is provided on the chain saw device. If the chain sawoperator forgets to operate the oil feeding pump, overheating, sticking,rapid wear and breakage of the saw chain may result.

It is an object of the present invention to provide an automatic oilingdevice which feeds small but effectively substantial quantities of oilresidue from the crankcase of the engine to the saw chain and to thegroove in which it travels.

It is an object of the invention to provide an oiling system whichutilizes oil from the oil containing gaseons fuel mixture which movesthrough the engine crankcase to the fuel inlet port in the side wall ofthe engine cylinder.

It is an object of the invention to provide an oil accumulator disposedadjacent to or in the fuel passage which leads from the crankcase alonga side of the engine cylinder to the fuel inlet port, this oilaccumulator being characterized by its ability to absorb lubricating oilfrom the fuel mixture, and there being means for intermittentlyreleasing oil from the oil accumulator into a duct which leads to thechain carrying groove in which the saw chain travels, thereby providingthese parts with ample lubrication without it being necessary for theoperator to work a lubricant pump.

It is an object of the invention to provide in a position along the pathof flow of the fluid mixture within the crankcase of the internalcombustion engine, an

oil collector comprising an oil absorbent structure hav-' ingcapillaries extending from one face thereof to another face thereof. Inthis device the oil collector is arranged so that the one face of theoil collector is exposed to the fuel mixture and the other face thereofis in communication with the oil outlet passage having therein means forpreventing reverse flow of fluids through the collector during thesuction cycle in the engine crankcase. Therefore, oil accumulates in thecollector during the suction and compression cycles within the crankcase, and small quantities of the oil are discharged from the collectorduring the compression cycles within the crankcase.

Further objects and advantages of the invention may be brought out inthe following part of the specification wherein many details aredescribed for the purpose of competence of disclosure without, however,intending to limit the scope of the invention which is defined by theappended claims.

Referring to the accompanying drawings which are for illustrativepurposes only:

Fig. 1 is a schematic elevational view showing an en gine powered chainsaw employing the invention;

Fig. 2 is an enlarged fragmentary section showing one embodiment of theinvention;

Fig. 3 is a fragmentary sectional view taken as indicated by the line3-3 of Fig. 2; and

Fig. 4 is an enlarged fragmentary sectional view showing an alternativeform of the invention.

Fig. 1 schematically shows a portable chain saw having an elongated flatblade 10 the periphery of which is provided with a groove along which asaw chain 11 travels. Power unit 12 is connected to the rear end of thebar 10 and includes a two cycle internal combustion engine 13 forsupplying power to rotate a sprocket, not

shown, which drives the chain 11 so as to cause it to travel around theperiphery of the blade 10.

As shown in Fig. 2, the engine 13 includes a cylinder 14, a crankcase 15and a crank 16 which is connected by 'a connecting rod 17 with a piston18 which reciprocates within the cylinder 14. The cylinder 14 has aportion 19 which extends into the crankcase 15 so that a fuel airpassage 20 is formed along the side of the cylinder portion 19 forconnecting the fuel air inlet 21 of the cylinder 14 with the crankcasespace 22 in which the crank 16 revolves.

An oil accumulator 23 is disposed so that one face 24 is arranged alongthe fuel air passage 20 of the crankcase. The oil accumulator 23comprises an approximately flat oil absorbent member or structure 25,the upper face 24 of which is arranged along the lower part of thepassage 20 and along the path of flow of the oil containing gaseous fuelair mixture which is moving, as indicated by arrows 26 from thecrankcase space 22 to the cylinder fuel inlet port 21.

The oil absorbent member 25 is characterized by having a multiplicity ofsmall spaces in which oil may accumulate, these spaces being in the formof capillaries which connect the upper face 24 of the member 25 with thelower face 27 thereof, so that oil which enters the cellular orcapillaceous oil collector member 25 may pass through the member 25 andbe subsequently discharged through a check valve 38' associated with anoutlet passage 28. Means 29 are provided through which oil leaving theoutlet passage 28 is delivered to a duct 30 for carrying the oil to thegroove of the saw bar 10 and to the chain to continuously maintain themin lubricated condition. a

The accumulator structure 23 is shown as comprising three plates 31, 32and 33 which are bolted onto the crankcase 16 so as to cover an opening34 in the lower wall of the crankcase opposite the inwardly projectingportion 19 of the cylinder 14. The oil collector 25 has a felt layer 35arranged between an upper screen 36 and a lower screen 37. At least theupper screen 3-6 is flocked so that it will have high absorbentqualities. The middle plate 32 is disposed against the lower screen 37and in its upper face has a shallow recess 38 which providescommunication of the upper end of the outlet opening 28 with the lowerface 27 of the oil collector 25. Means are provided for controlling theflow of oil from the collector 25 through the outlet opening 28. Thiscontrol means responds to pressure within the crankcase 15 during thecompression cycle therein. In the simple form disclosed, the flowcontrolling means comprises a reed valve 38' secured to the lower faceof the plate 32 by rivets 39 and being posi-, tioned so that itsfree'end 40 covers the lower end ofthe outlet opening 28. The plate 33covers. the reed outlet opening 28 to the duct 30.

The direction of rotation of the crank 16 is indicated by an arrow 42.As the crank moves downwardly from the position in which it is shown thepiston 18 will be moved outwardly in the cylinder, and this movement ofthe piston. willact -to draw'thefuel mixture into the crankcase space22, at a time when the piston 18 is com during the compression cycle,the pressure acting down wardly through the collector 25'will cause asmall flow of oil outwardly through the outlet opening 28, depressingthe free end 40 of'the reed valve 38' downwardly so that the oil willpass the reed valve and enter the passage 41. During the suction cyclewithin the crank case-space 22 there will be no flow of fluid upwardlyfor the reasonthat the reed valve 38 will return to its posi-' tionclosing the outlet opening 28, thereby acting as a check valve toprevent upward flow of fluid from the outlet opening 28 and through theoil collector. Therefore, it is only the downwardly acting pressure.difierenti-al applied to the oil collector 25 during the compres sioncycle within the crankcase space 22 which can eifect movement of oilthrough the collector 25,-and since this movement of oil is in outwardor downward direction, there results an intermittent feeding of oil pastthe valve 38 through the passage 41-to the duct 30 which leads to theparts which are to be lubricated. The oil feeding means 23 is placed insuch relation to the rotation of the crank 16 and to the space 22 thatsmall oil droplets in the fuel mixture are thrown downwardly andleftwardly so that they accumulate and flow downwardly along the lowercrankcase wall or directly through themouth of the passage 20 to the oilcollector 25.

In order to feed the oil quite rapidly and in spaced quantities or slugsthrough the duct 30, the invention also provides means, 'as shown inFig. 4, for feeding small. quantities of gas-into the entrance of theoil de-- livery duct 30, it being understood that the invention may bepracticed with or without this gas feeding means. This gas oil slugsystem can be accomplished in one of two ways. First, by properlyproportioning the area-, and thickness of the oil absorbing pads withthe size and stiffness of the outlet check valve, and size of associatedpassages, so that the pad is substantially purged of oil on each cyclewhich allows some gas to flow through the pad and check valve also. Thisresults in a small quantity of oil followed bya larger slug of gas whichacts an oil accumulator contiguous to said passage exposed to the oilcontaining, gaseous fuel mixture which flows through said passage, saidoil. accumulator comprising an oil collector in which oil from themixture accumulates; walls forming an outlet passage for conducting oilfrom said oil collector, said outlet passage being adapted to beconnected to a duct for conveying oil to the chain of the chain sawdevice; fluid flow controlling means operating in said. passage tocontrol the flow of oil from said oil collector; and means operating inresponse to periodic increases in gas pressure in said crankcase due torecipro cation of the piston of the engine to admit spacedquantities ofgas into said duct to separate the oil flow therein into spacedquantities.

2. In an automatic chain oiling means for a chain saw device having atwo cycle engine provided with a cylinder having a fuel inlet port inthe side wall thereof and a fuel passage leading from the enginecrankcase along the side of the. cylinder to. the fuel inlet'opening::an oil collector. contiguous to said passage, "comprising an oilabsorbentbody havinga face thereof exposed to the oil containing,gaseous fuelmixture in said passage;- walls forming an. outlet passagecommunicating with another face ofsaidiabsorbentbody for receiving oilfrom the interior of said-crankcase as the. gas pressure in.

as a rapid carrier of the oil through the feed line. The

second' method may embody additional check valve means as follows.Adjacent one end of the oil collector 25, a gas passage 45 is extendedthrough the members 31, 32 and 33, to connect the interior of thecrankcase 15 with the passage 41', and a yieldable valve means 46 isarrangedto close the lower end of the passage 45 during the suctioncycle in the crankcase 15, but to permit a small flow of gas from theinterior of the crankcase 15 into the passage-41 during the compressioncycle in the crankcase 15. The valve means 46 is a flexible reed valvesubstantially the same as the reed valve 38' and'is secured in aposition wherein its free end covers the lower end of the passage 45 byrivets 47. The result of the arrangement described is that consecutivequantities of oil and gas move through the duct 30 to the point ofapplication of the oil.

1 Iclaim:

1.'In an automatic chain oiling means for a chain saw device having atwo cycle engineprovided with a cylinder'having a fuel inlet port in thesidewall thereof and;a. fuel passage leading from the engine crankcasealong .the side oflthe cylinder to the fuel inlet opening? saidcrankcase fluctuates dueto thereciprocation of the pistonof the engine;and acheck .valve connected to said gas passage for preventing flow ofgas from said duct throughpsaid gas passageinto said crankcase.

3. In an automatic chain oiling means for a chain saw device having atwo cycle engine providedwithan oil-. fuel receiving crankcase: an oilcollector communicating with said crankcase comprising. an oilabsorbentbody having a face thereof exposed to the interior of said crankcase anda wall formingv an oil collectingcharnber adjacent another face of saidabsorbent body,.said chamber having an opening for oil adapted tobetconnected' to a duct for carrying oil to the saw chain; check.valvemeans for preventing reverse flow through saidch'amber; and meansfor admitting spaced quantitieszof air into saidduct to separate the oilflow therein into spaced quantities.

4; A device as defined in claim 3 whereinxsaid'means for admittingspaced quantities of air. to. saidduct comprises means forming a portconnecting said. duct with the interior of said. crankcaseindependentlyof said absorbent body, andvalve means for controlling the-flow of airthrough said port.

5. In an automatic oiling device for-use with an internal combustionengine: an oil collector communicating with a crankcase of said engine,said collector having an outlet opening adapted to be connectedto a ductfor carrying the oil away from said collector, means for feeding spacedquantities of air into said duct to separate the 'oil flow therein intospaced quantities, said means for. feeding spaced flows of air into saidduct comprising means forming a port connecting said duct with theinteriorof the crankcaseof the engine independently of said collector,and valve means for controlling the flow of air through said port.

References Citedin the file of this patent V UNITED STATES PATENTS1,214,396 Wainwright Jan. 30,1917 2,288,426 Stack June 30, 19422,605,787 Kiekhaefer Aug. 5, 1952 2,682,259 Watkins June 29, 1954'

